The question asked in the assignment is above with the correct answers in the bo

Question

The question asked in the assignment is above with the correct answers in the boxes, and the solution below. My question is where did the number 0.622 come from? It has got me stuck and I can't solve the rest of the problem without knowing whre that came from.

A buffer prepared by dissolving oxalic acid dihydrate (H2C204 2H20) and disodium oxalate (Na2C204) in 1.00 L of water has a pH of 4.445. How many grams of oxalic acid dihydrate (MW 126.07 g/mol) and disodium oxalate (MW 133.99 g/mol) were required to prepare this buffer if the total oxalate concentration is 0.299 M? Oxalic acid has pKa values of 1.250 (pKat) and 4.266 (pka2) Number Mass of H20204. 2H20 7.5 Number Mass of Na2C204 32.1

Explanation / Answer

I'm assuming you are asking about 0.662 instead of 0.622

Here is how it came,

pH = pKa + log[C2O42-]/[HC2O4-]

4.445 = 4.266 + log[C2O42-]/[HC2O4-]

4.445-4.266 = log[C2O42-]/[HC2O4-]

0.179 = log[C2O42-]/[HC2O4-]

[C2O42-]/[HC2O4-] = 100.179

[C2O42-]/[HC2O4-] = 1.51

[C2O42-] =1.51[HC2O4-]

[HC2O4-] = (1/1.51)[C2O42-]

[HC2O4-] = 0.662[C2O42-]

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.